By Catherine McNeurThe Tree of Heaven, or Ailanthus, gained fame in 1943 as a symbol of endurance in Betty Smith’s A Tree Grows in Brooklyn. In this book about a plucky, determined girl from the tenements of Brooklyn, the tree seemed to embody her spirit. It thrived in cities while other plants withered. As Smith put it, “No matter where its seed fell, it made a tree which struggled to reach the sky. It grew in boarded-up lots and out of neglected rubbish heaps and it was the only tree that grew out of cement. It grew lushly, but only in the tenement districts.” Today, if you ask an urban forester about Ailanthus trees, you’ll find that it’s exactly that kind of resilience that they find most frustrating. Today the Tree of Heaven is considered an invasive species and a problem to be solved. This was not always the case.

While New York’s municipal government did not always embrace street trees in its early history, sometimes classifying them as traffic obstructions standing in the way of development, hearts and minds began to change in the 1820s and 1830s as the population skyrocketed and new streets were laid. Tree advocates argued that they were a way to ornament the sidewalks, provide shade, and also infuse crowded, epidemic-prone cities with fresh air. Trees also seemed to improve real estate values. Without support or organization on the municipal level, newspapers frequently encouraged homeowners to plant trees, reminding them every spring and fall when the planting season had arrived, and reiterating the many reasons property owners might fill out the urban canopy. Horace Greeley, for instance, called on “Young Men or citizens of slender pecuniary means” who read the New-York Daily Tribune to buy property in uptown Manhattan and transform it into something worthy of pride. The first step? Trees.Could any tree species survive on the busy streets of a city? This was a big question for these homeowners. It wasn’t just about trees that could grow vertically enough that they wouldn’t pose problems for buildings, or trees whose roots wouldn’t disrupt the newly dug water pipes, gutters, or paving stones. It was also about finding a tree that could thrive despite these urban improvements, and the seemingly despoiled environment around it.The time it would take to have a sizable tree was also an issue. Early nineteenth-century nursery catalogues highlighted the desire among urban dwellers to have an instant urban canopy. One of the first commercial nurseries in the country was the Prince Nursery in Flushing, Queens. As they shipped plants throughout the United States and overseas, they were particularly central to the widespread adoption of the exotic Chinese Ailanthus trees. They also catered to a local market. The Tree of Heaven first appeared in their annual catalogue in 1823 where it got the star treatment. While most of the trees sold in the range of 37.5 to 50 cents, the Ailanthus was one of just a handful that sold for the highest price: $1 per tree. Initially, William Prince mistook the tree for a Tanner’s Sumach, but once they corrected the name highlighting its exotic origins in China, Prince’s son gleefully recalled that “every one gazed on it with wonder and admiration, and for many years it was impossible to supply the demands at treble the former prices.” Ailanthus trees were incredibly popular.In their catalogue, the Prince nursery organized their deciduous ornamental trees into classes based on how fast and large the trees would grow. The Tree of Heaven also stood out among the other trees on the list as having an extended description, praising the tree’s four-foot long leaves, its immense height, and ability to withstand “the greatest heat uninjured, [retaining] its foliage until very late in the season.” What more could you ask for? When speculators and homeowners wanted to quickly improve the look of their streets, gain instant shade during the sweltering summer, and improve air quality in a sickly city, the Prince Nursery could show them how to achieve exactly what they wanted.Not only could the Ailanthus grow quickly, it was also able to resist inch worms, a major perk in mid-nineteenth century American cities. From the mid-1850s through the 1870s, several East Coast cities, including New York and Brooklyn, were hit with inch worm infestations. Alternatively called cankerworms or measure worms, the inch worms quickly defoliated most of the shade trees in the cities, dangled down from branches, falling onto pedestrians’ hair, mustaches, and clothing, or onto sidewalks where they were squished into an unappealing mush beneath people’s shoes.

Nuisance as they were when they clung to your mustache, the inch worms’ defoliation of so many of the city’s street trees posed real problems. Prior to air conditioning or electric fans, these trees helped to shade sidewalks and homes during oppressively hot days. However, if the worms denuded the trees by late June or early July, that benefit was completely gone right when it was most needed. The Brooklyn Horticultural Society described the aesthetic threat that these worms posed in a pamphlet plotting a war on worms:

Such shade-trees as ours are to a city what the hair is to the human head; its natural drapery, its crowning ornament. And to have these graceful and luxuriant tresses of foliage, which shelter and shadow our stony pathways, either swept away from them or converted into dirty cobwebbed nests of filthy vermin, would be a great disaster, as well as a disgrace. Business must be diminished by it, as well as pleasure. The attractiveness of the city as a place of residence must be seriously impaired, and its whole prosperity be, in the end, seriously affected.

Bald is not beautiful, in other words, according to these horticulturists. They clearly saw the ravenous worms as a major threat to the city in terms of its economy, aesthetics, “the purity of its air and the fresh cleanliness of its embowered streets and squares.” The worms needed to be conquered.While the inch worm delighted in the tasty leaves of the European Linden, Silver-leafed Maple, Sugar Maple, English Elm, Horse Chestnut, Weeping Willow, Silver-leafed Poplar, English Ash, and Honey Locust — in short, some of the most popular street trees in Brooklyn and most other American cities — the Ailanthus was hardly affected. For this, journalists, horticulturists, doctors, and everyday city residents celebrated the Tree of Heaven as a saving grace for urban worm problems.The worm-proof nature of the Ailanthus hardly qualified as a perk to critics who despised its summer odor. The male version of the tree had a particular vile smell for about two weeks each summer, causing many to blame their headaches and allergy-like symptoms on the odor. One mother wrote to the New York Times pinning her five children’s near-death states on the tree, as the “poisonous effluvia of this loathsome Ailanthus” that filled the children’s nursery, causing them to vomit and faint. In epidemic-prone times, anxiety over miasmas and the brief but foul odors of this tree is understandable. Given street trees’ close proximity to buildings and the noses of hundreds of thousands of city residents, it was hard to deny that the “stink tree” might not be well suited for cities, after all. Along these lines, Congress ordered that DC no longer plant Ailanthus trees in 1853. Following a recommendation from the city’s Board of Health, Congress voted that they would allot funds for improving the city’s trees, landscaping, and pavements as long as the landscapers did not plant Ailanthus trees.

In "Washington Square," Henry James described the extensive presence of Ailanthus in the park in the 1830s. On the left part of this image from 1917, there seems to be an Ailanthus tree in Washington Square where they so long dominated, though it’s hard to identify it precisely. Courtesy of the Irma and Paul Milstein Division of United States History, Local History and Genealogy, The New York Public Library.

Inspired by the bold actions of tree control in DC, many other cities took aim at the Ailanthus, hoping to enact even stricter laws locally. The writers for the New York Timeswere particularly outspoken in their deep hatred for the scent of the Ailanthus. Though they advocated for the city to enact a law calling for their removal, this solution was improbable, given that trees were almost exclusively planted by private individuals and the city government had neither the funding nor the manpower to take on such an enormous and likely contentious project. The article, however, ended with a call to all New Yorkers to fix the problem on their own: “Every man who has an ailanthus tree in his neighborhood, should make it his duty to destroy it.” A flurryofletterstotheeditor soon followed that both defended and criticized the tree, making it clear that many people had very passionate opinions about its value and place in the city.

The notorious odor of the Ailanthus seemed inextricably tied to the fact that it was a foreign plant. Famed landscape architect Andrew Jackson Downing penned an article for his Horticulturist magazine in 1852 right before his untimely death on a steamboat, declaring “Down with the Ailanthus!” He ominously described how the Tree of Heaven had “penetrated all parts of the union,” and was only beginning to show its true character. Downing clearly tied his hatred for the tree with ethnic bigotry when he wrote that the tree “has the fair outside and treacherous heart of the Asiatics.”

Downing, who had once been quite a fan of the Ailanthus, now objected to it, seeing how it suckered on its own and escaped the control of even the most diligent gardeners. Mostly, though, he was offended by its very foreignness:"we confess openly, that our crowning objection to this petted Chinaman or Tartar, who has played us so falsely, is a patriotic objection. It is that he has drawn away our attention from our own more noble native American trees, to waste it on this miserable pigtail of an Indiaman." Other critics of the tree took heed of Downing. Anticipating the Ailanthus’ modern status as an invasive exotic, the New York Times called it a “filthy and worthless foreigner” and proudly declared they were “Know-Nothings” when it came to the tree — a reference to the anti-immigrant political party of the time. The New York Tribune similarly called for the xenophobes to take action: “Where are the Know-Nothings? Here is a legitimate field for them; let them rid us of this foreign tree, and in its place we will have one that does not stink — one of American growth.” Not only were the journalists making statements about the appropriateness of foreign plants in American cities, but also foreign people.

Still, the worms basically saved the Ailanthus, inasmuch as the trees won acclaim by avoiding the worms’ depredations. Many defenders of the tree made a point of noting its ability to fend off worms. “Julia,” who wrote a letter to the New York Times in response to their call to cut them all down, noted: “It is beautiful to the eye, refreshing as a shade, of quick growth — but above all, it is alwaysfree from those jumping or measuring worms which destroy so many of our forest trees, and of which, any observer in our City will notice, hardly one escapes their ravage.” Julia gained a lot of critics for her defense, some inferring she was an indecent woman, not unlike one who might smoke cigars, who likely lacked olfactory nerves. Still, others joinedher defense. Most importantly, perhaps, the trees themselves withstood the depredations of worms, and that helped to secure their place in the urban canopy.

By 1862, the Ailanthus was the most common street tree in Brooklyn, by no small margin. The Brooklyn Horticultural Society found 18 species of trees on the streets from elms to buttonwoods, but the Ailanthus made up more than 43% of the canopy. The next most popular tree, the European Linden, which had been particularly fashionable in the early decades of the nineteenth century, made up just 14%. The Ailanthus was clearly thriving in urban environments. And this wasn’t just the case in Brooklyn. As the decades went on, the Ailanthus went from exotic to downright common. Cities across the country from San Francisco to Atlanta had Ailanthus trees taking root.

Ailanthus trees remain a persistent presence in New York despite many attempts to remove them since the 1850s. Using the 2005 tree census, artist/developer Jill Hubley has mapped tree species throughout New York, including the Tree of Heaven, seen here. Courtesy of Jill Hubley.

The fact that the Ailanthus could stand up to the sooty air of coal-fueled industrialization when other trees withered, rooted it in American cities in the late nineteenth and early twentieth century. It seemed to grow where nothing else could, and it became most deeply embedded in sidewalk cracks, in overgrown lots, and behind tenements just like Francie Nolan’s in A Tree Grows in Brooklyn. It had evolved over the century from one of the most expensive trees in Prince’s catalogue to, as Betty Smith put it, a tree that “liked poor people.” The tree also sprouted up where no one had planted it. With an aggressive suckering nature, a grove of Trees of Heaven could sprout up within a few years in an untended piece of land. Even more frustrating for those trying to rid themselves of Ailanthus trees, if attempts were made to chop them down, the Ailanthus would grow back all the more furiously, sending up suckers from its roots at multiple locations.

​Their independence from human control and simultaneous closeness to humans, their presence in urban pollution, their offensive odor, their siding up against inexpensive real estate, their exotic heritage — all of this has made Trees of Heaven “weeds” in many minds. They symbolically represented a lack of cultivation — something we rarely celebrate in landscapes, especially urban landscapes.

​With the exception of unexpected natural disasters, urban environments often have the aura of being controlled spaces. But the Ailanthus managed to defy these perceptions. They served a particular purpose in the early nineteenth century, providing nearly instant shade that didn’t require a generation of patience on the recently paved streets of a rapidly growing city. They also thrived despite the exigencies of the urban environment — pavement inching too close to their roots, innumerable worms hungry for leaves, and the heavy smoke of coal-fueled industrialization.

Ailanthus trees in a common habitat in 2017, edging up on a fence among dumpsters and graffiti. Photo: Catherine McNeur.

New Yorkers could celebrate the pluck and resilience of plants and people who thrived in conditions that seemed unhealthy or unwelcoming. Or they could look down on the organisms that were so durable as to make such spaces their home. One way or another, the Ailanthus didn’t care what people thought. In thriving without or even despite human intervention, the tree clearly communicated that no matter what governments or residents wanted, they would continue to persist, keeping parts of the urban environment beyond control.Catherine McNeur is Associate Professor of History at Portland State University and award-winning author of Taming Manhattan: Environmental Battles in the Antebellum City.